docs: cut v0.21.4 — replay-scrubbing accessibility

Patch release for the three post-v0.21.3 commits on the B-2 replay
screen-takeover redesign arc. One through-line: the replay overlay
gains scrubbing affordances. The player can see at a glance where
the winning move sits (WIN MOVE marker on the scrub bar) and stop
on any move to inspect the board (pause / resume / step controls
plus a Space keyboard accelerator).

Also adds the data foundation that makes the marker possible:
`Replay::win_move_index: Option<usize>`, an additive serde-default
field that doesn't bump `REPLAY_SCHEMA_VERSION` because legacy
on-disk replays load with `None` and simply don't get a marker.

Remaining B-2 work — screen-takeover layout, move-log scroller,
mini-tableau preview — shares a layout-reflow prerequisite the
banner-only overlay can't carry, so it's deferred to a future
cycle that can take it as a single multi-session arc.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,9 +6,130 @@ project follows [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
-No threads in flight. v0.21.3 cut on 2026-05-08; CHANGELOG accumulates
+No threads in flight. v0.21.4 cut on 2026-05-08; CHANGELOG accumulates
 the next cycle here.
 
+## [0.21.4] — 2026-05-08
+
+Patch release for the post-v0.21.3 work. One through-line:
+**replay-scrubbing accessibility**. The replay overlay used to be
+pure-passive — the player started a replay, watched it execute,
+and waited for it to end. v0.21.4 adds the scaffolding for
+*navigating within* a replay: a WIN MOVE marker on the scrub bar
+so the player can see at a glance where the winning move sits,
+and pause / resume / step controls so they can stop on any move
+and inspect the board.
+
+The work is also the first three commits on the B-2 replay
+screen-takeover redesign arc. The remaining pieces (screen-
+takeover layout, move-log scroller, mini-tableau preview) are
+deferred to a future cycle because they need a layout reflow
+that the existing banner-only overlay can't carry.
+
+### Added
+
+- **`Replay::win_move_index: Option<usize>` data field**
+  (`ab857bb`). Additive optional field on the persisted
+  `Replay` shape. `#[serde(default)]` keeps older
+  `latest_replay.json` / `replays.json` files loadable without
+  bumping `REPLAY_SCHEMA_VERSION` — this is purely additive.
+  Populated at the live recording site
+  (`game_plugin::handle_game_won`) via a new builder-style
+  setter `Replay::with_win_move_index`. For fresh recordings
+  the value is always `Some(moves.len() - 1)` because recording
+  freezes on win, but storing it explicitly lets the playback
+  UI read the WIN MOVE position directly without re-deriving
+  on every render.
+- **WIN MOVE scrub-bar marker** (`52befa6`). New
+  `ReplayOverlayWinMoveMarker` component spawned as a sibling
+  to `ReplayOverlayScrubFill` under the 1px scrub track,
+  absolute-positioned at `replay.win_move_index / total %` of
+  the bar. Painted in `STATE_SUCCESS` (green) so the marker
+  reads as "this is where the win lives." Pure helper
+  `win_move_marker_pct` returns `None` for any state where the
+  marker shouldn't draw (Inactive, Completed, replay missing
+  the field, empty move list); percentage clamps to `[0, 100]`
+  defensively. Spawn-time only — the position never changes
+  during a single playback because the underlying `Replay` is
+  immutable while `Playing`.
+- **Pause / Resume / Step playback controls** (`fbe48ac`). New
+  `paused: bool` field on `ReplayPlaybackState::Playing`.
+  `tick_replay_playback` skips the `secs_to_next` decrement
+  entirely while paused so cursor and timer freeze together;
+  resuming starts the next move from a full interval. New
+  public API: `toggle_pause_replay_playback` and
+  `step_replay_playback` (the latter hard-gated to `Playing {
+  paused: true }` via the destructure pattern itself, so
+  manual stepping can't race the tick loop). On-screen Pause
+  and Step buttons sit alongside the existing Stop button;
+  `Space` keyboard accelerator toggles pause / resume.
+- **`Replay::with_win_move_index` builder** (`ab857bb`).
+  Chainable setter so the recording site can write
+  `Replay::new(...).with_win_move_index(idx)`. Keeps
+  `Replay::new`'s signature stable across the 13+ existing
+  test-fixture call sites that don't care about the field.
+
+### Changed
+
+- **`Replay::new` writes `win_move_index: None`** (`ab857bb`).
+  Existing canonical constructor stays signature-compatible
+  with all existing callers. The field is opt-in via the
+  builder.
+- **`game_plugin::handle_game_won` populates the new field**
+  (`ab857bb`). The recording site computes
+  `recording.moves.len().checked_sub(1)` as the win-move
+  index. `checked_sub` rather than direct subtraction guards
+  the unreachable empty-recording branch (which is also
+  guarded earlier in the function).
+- **`tick_replay_playback` honors the new `paused` flag**
+  (`fbe48ac`). Skipping the timer decrement is the only
+  behavior change; the loop body and Completed-detection are
+  unchanged. Stepping fires moves directly via
+  `step_replay_playback`, bypassing the tick path entirely.
+- **Pause / Resume button label is reactive** (`fbe48ac`).
+  `update_pause_button_label` walks `Children` from the
+  marked button to its inner `Text` and repaints the label
+  whenever `ReplayPlaybackState` changes. Pure helper
+  `pause_button_label` covers all four state arms (running,
+  paused, inactive, completed).
+- **25 existing `Playing { ... }` construction sites gained
+  `paused: false`** (`fbe48ac`). Mechanical edit across
+  `replay_overlay`, `achievement_plugin`, and
+  `replay_playback` tests to satisfy the new field
+  requirement. No behavioral change.
+
+### Documentation
+
+- `SESSION_HANDOFF.md` refreshed three times this cycle —
+  once after each post-cut feature commit. The B-2 entry in
+  the Visual-identity follow-ups list now points at the
+  remaining sub-pieces (screen-takeover layout, move-log
+  scroller, mini-tableau preview) as a single multi-session
+  arc rather than three independent ones, since they share a
+  layout-reflow prerequisite.
+
+### Stats
+
+- **1228 passing tests / 0 failing** across the workspace
+  (net +21 from v0.21.3's 1207 baseline):
+  - 5 from `ab857bb`'s `win_move_index` coverage: default
+    constructor, builder set / set-None, on-disk round-trip,
+    legacy-JSON-loads-with-None backward-compat. The last
+    test pins the no-schema-bump claim — if a future refactor
+    drops the `#[serde(default)]`, that test catches it.
+  - 8 from `52befa6`'s WIN MOVE marker: pure-helper truth
+    table (Inactive / Completed / no-field / correct-position
+    / clamp) + spawn-presence-with-field /
+    spawn-absence-without / despawn-with-overlay observables.
+  - 8 from `fbe48ac`'s playback controls: label truth table,
+    label repaint on state change, click-toggles-paused,
+    step advances cursor by exactly one with paused
+    preserved, step-while-running no-op, Space toggles
+    paused.
+- Zero clippy warnings under `cargo clippy --workspace
+  --all-targets -- -D warnings`.
+- `cargo test --workspace` clean.
+
 ## [0.21.3] — 2026-05-08
 
 Patch release for the post-v0.21.2 work. One through-line:

SESSION_HANDOFF.md

@@ -1,73 +1,91 @@
 # Solitaire Quest — Session Handoff
 
-**Last updated:** 2026-05-08 — v0.21.2 cut and tagged at `f23df3b`;
+**Last updated:** 2026-05-08 — **v0.21.3 cut and tagged at
-post-cut work shipped: Toast Warning (`279e23d`) and the HC
+`3d92a91`**, working tree clean, all post-tag work pushed to
-dynamic-paint rollout (`c153363`). Working tree clean, all
+origin.
-post-tag work pushed to origin.
 
-v0.21.2 is a patch release for the post-v0.21.1 polish work:
+v0.21.3 is a patch release with one through-line: **accessibility
-extends accessibility (full HC chrome rollout across 8 surfaces;
+arc closure**. v0.21.2 explicitly carved out "dynamic-paint sites"
-splash reduce-motion gating on scanline + cursor pulse), adds a
+(HUD action buttons, modal buttons, radial menu rim) on the
-floating MOVE chip above the destination card during replay
+assumption that their existing paint cycles would race the
-playback, and lights up the first real consumer of
+central `update_high_contrast_borders` system. v0.21.3 walks the
-`ToastVariant::Error` (a "Invalid move" toast as the third leg
+actual code, finds the carve-out was over-cautious, and closes
-of the existing audio + visual rejection-feedback stool).
+it. Bonus: the first real consumer of `ToastVariant::Warning`
+also lands here, making the `ToastVariant` enum fully load-bearing
+(every variant has at least one driver).
 
-Full v0.21.2 detail lives in `CHANGELOG.md` § [0.21.2]. This
+Full v0.21.3 detail lives in `CHANGELOG.md` § [0.21.3]. This
 file from here on focuses on what's *open* post-cut and how to
 resume.
 
 ## Status at pause
 
 - **HEAD locally:** see `git rev-parse HEAD`. The cut commit is
-  `f23df3b`; post-cut work (`279e23d` Toast Warning, `c153363`
+  `3d92a91`; post-cut work on B-2 (`ab857bb` data field +
-  HC dynamic-paint rollout) rides on top of that.
+  `52befa6` WIN MOVE marker UI + `fbe48ac` playback controls)
-- **HEAD on origin:** matches local. v0.21.2 is fully on origin.
+  rides on top of that.
+- **HEAD on origin:** matches local. v0.21.3 is fully on origin.
 - **Working tree:** clean. No WIP outstanding.
 - **`artwork/` directory:** still untracked. Intentional.
 - **Build:** `cargo clippy --workspace --all-targets -- -D warnings`
   clean.
-- **Tests:** **1207 passing / 0 failing** across the workspace
+- **Tests:** **1228 passing / 0 failing** across the workspace
-  (net +12 from the v0.21.2 cut: 8 from Toast Warning wiring;
+  (1207 from v0.21.3's stats + 5 from `ab857bb`'s
-  4 from the radial-rim HC truth-table).
+  `win_move_index` coverage + 8 from `52befa6`'s WIN MOVE marker
-- **Tags on origin:** `v0.9.0` through `v0.21.2`. v0.21.2 is on
+  pure-helper truth-table + spawn lifecycle + 8 from `fbe48ac`'s
-  `f23df3b`; v0.21.1 stays on `daa655a`; v0.21.0 stays on
+  pause / step / keyboard accelerator coverage).
-  `04f9bf9`; v0.20.0 stays on `41a009a`.
+- **Tags on origin:** `v0.9.0` through `v0.21.3`. v0.21.3 is on
+  `3d92a91`; v0.21.2 stays on `f23df3b`; v0.21.1 stays on
+  `daa655a`; v0.21.0 stays on `04f9bf9`; v0.20.0 stays on
+  `41a009a`.
 
-## Since the v0.21.2 cut
+## Since the v0.21.3 cut
 
-- **`279e23d` — Toast Warning variant wired.** First in-engine
+- **`ab857bb` — `Replay::win_move_index` data field landed.**
-  consumer of `ToastVariant::Warning`: a 4 s amber-bordered
+  First finite step toward the B-2 replay screen-takeover
-  toast that fires once per daily-challenge date when the
+  redesign. Additive optional `Option<usize>` on `Replay` with
-  player is within 30 min of UTC midnight reset and hasn't yet
+  `#[serde(default)]` so older `latest_replay.json` /
-  completed today's challenge. Mirrors the v0.21.2 Toast Error
+  `replays.json` files load unchanged (no schema bump). Populated
-  pattern — a domain message (`WarningToastEvent(String)`) is
+  at the live recording site via a new `with_win_move_index`
-  the contract between the daily plugin and the animation
+  builder; for fresh recordings the value is always
-  plugin's spawn handler. Suppression decided by a pure helper
+  `Some(moves.len() - 1)` because recording freezes on win, but
-  (`compute_expiry_warning_minutes`) that's exhaustively tested
+  storing it explicitly lets the playback UI read the WIN MOVE
-  without an `App`. After this commit every `ToastVariant`
+  position directly without re-deriving on every render. 5 new
-  (Info / Warning / Error / Celebration) has at least one real
+  tests (1207 → 1212): default, builder set / set-None, on-disk
-  driver — the variant enum is fully load-bearing.
+  round-trip, legacy-JSON-loads-with-None backward-compat.
-- **`c153363` — HC rollout to the dynamic-paint sites.** Closes
+- **`52befa6` — WIN MOVE marker on the scrub bar.** Second
-  the v0.21.2 carve-out. Re-reading the code revealed only one
+  commit on B-2 — the UI that consumes the data field. New
-  of three "dynamic-paint" sites was actually a border-paint
+  `ReplayOverlayWinMoveMarker` component spawned as a sibling
-  cycle — HUD action buttons and modal buttons paint
+  to `ReplayOverlayScrubFill` under the 1px scrub track,
-  *backgrounds* dynamically with static borders, so they take
+  absolute-positioned at `replay.win_move_index / total` along
-  the existing `HighContrastBorder` marker pattern cleanly. The
+  the bar. Painted in `STATE_SUCCESS` (green) so the marker
-  radial menu rim is the only true dynamic-painter (full
+  reads as "this is where the win lives." Pure helper
-  per-frame respawn of `Sprite` entities); HC is folded into
+  `win_move_marker_pct` returns `None` for any state where the
-  the spawn there with a pure helper (`radial_rim_outline`)
+  marker shouldn't draw (Inactive, Completed, replay missing
-  that boosts the *focused* rim to `BORDER_SUBTLE_HC` under HC
+  the field, empty move list); percentage clamps to `[0, 100]`
-  rather than `BORDER_STRONG` — naive marker substitution would
+  defensively. Lifecycle is spawn-time only — the marker is
-  invert the focused-vs-resting hierarchy because
+  immutable during a single playback because the underlying
-  `BORDER_SUBTLE_HC` (#a0a0a0) is lighter than `BORDER_STRONG`
+  `Replay` doesn't change while `Playing`. Despawned with the
-  (#505050). After this commit, every UI surface in the v0.21.x
+  overlay tree on transition back to `Inactive`. 8 new tests
-  accessibility arc either carries the marker or has HC folded
+  (1212 → 1220): pure-helper truth table + spawn-presence /
-  into its own spawn cycle. No "un-tagged because race-risk"
+  spawn-absence / despawn-lifecycle observables.
-  surfaces remain.
+- **`fbe48ac` — playback controls (pause / resume / step).**
-
+  Third commit on B-2. New `paused: bool` field on
-For the v0.21.2 contents themselves, see `CHANGELOG.md` §
+  `ReplayPlaybackState::Playing`; `tick_replay_playback` skips
-[0.21.2].
+  the `secs_to_next` decrement entirely while paused so cursor
+  and timer freeze together. New public API:
+  `toggle_pause_replay_playback` and `step_replay_playback`
+  (the latter hard-gated to `Playing { paused: true }` so
+  manual stepping can't race the tick loop). UI: Pause /
+  Resume button (label repaints reactively via
+  `update_pause_button_label` which walks `Children` from
+  marker to inner `Text`) + Step button + Space keyboard
+  accelerator. Existing 25 `Playing { ... }` construction
+  sites across tests gained `paused: false` mechanically.
+  8 new tests (1220 → 1228): label truth table, label repaint
+  on state change, click-toggles-paused, step advances exactly
+  one cursor with paused preserved, step-while-running no-op,
+  Space toggles paused.
 
 ## Open punch list
 
@@ -105,11 +123,14 @@ palette refresh all shipped in v0.20.0 + v0.21.0. What stays open:
   a WIN MOVE marker on the scrub bar. Banner-local pieces all
   shipped in v0.21.0 (`c84d9f4` + `6204db8` + `54005d5` +
   `e080b49`); the floating MOVE chip above the focused card
-  shipped in v0.21.2 (`2fb2d63`). The screen-takeover is a
+  shipped in v0.21.2 (`2fb2d63`). The WIN MOVE scrub-bar marker
-  multi-session redesign with data-layer impact — needs a new
+  shipped post-v0.21.3 in `ab857bb` (data field) + `52befa6`
-  `win_move_index: Option<usize>` field on `Replay` (currently
+  (UI). Playback controls (pause / resume / step + Space
-  unimplemented), a move-log scroller, and a mini-tableau
+  accelerator) shipped post-v0.21.3 in `fbe48ac`. What still
-  preview.
+  needs to land: a move-log scroller and a mini-tableau
+  preview — both screen-takeover-only pieces that need a
+  larger layout reflow than the existing banner can carry.
+  Multi-session.
 - *Floating `MOVE N/M` chip above the focused card during
   playback — closed 2026-05-08 by `2fb2d63`.* World-space
   `Text2d` entity sibling to the banner overlay; uses the same
@@ -252,22 +273,20 @@ into a v0.21.1 / v0.22.0 cut.
 ```
 You are a senior Rust + Bevy developer working on Solitaire Quest.
 Working directory: <Rusty_Solitaire clone path on this machine>.
-Branch: master. v0.21.2 is tagged at f23df3b (cut 2026-05-08, a
+Branch: master. v0.21.3 is tagged at 3d92a91 (cut 2026-05-08, a
-patch release rolling up accessibility extensions, replay polish,
+patch release rolling up the accessibility-arc closure: HC reaches
-and the first real `ToastVariant::Error` consumer). v0.21.1 stays
+the previously-carved-out dynamic-paint sites, and the first real
-at daa655a, v0.21.0 at 04f9bf9. Working tree clean. Post-cut
+consumer of `ToastVariant::Warning` lands as the daily-challenge
-work shipped: Toast Warning variant (`279e23d`) and the HC
+expiry toast). v0.21.2 stays at f23df3b, v0.21.1 at daa655a,
-dynamic-paint rollout (`c153363`) — accessibility arc is fully
+v0.21.0 at 04f9bf9. Working tree clean. See CHANGELOG.md §
-closed, every `ToastVariant` has at least one real driver. See
+[0.21.3] for full detail.
-CHANGELOG.md § [0.21.2] + the "Since the v0.21.2 cut" section
-above for full detail.
 
 State: HEAD locally — see `git rev-parse HEAD`. All workspace tests
 pass (1207+; check with `cargo test --workspace`), clippy clean.
 
 READ FIRST (in order, before doing anything):
   1. SESSION_HANDOFF.md  — this file
-  2. CHANGELOG.md        — [0.21.2] section is the most recent cut
+  2. CHANGELOG.md        — [0.21.3] section is the most recent cut
   3. CLAUDE.md           — unified-3.0 rule set
   4. CLAUDE_SPEC.md      — formal architecture spec
   5. ARCHITECTURE.md     — crate responsibilities + data flow
@@ -288,10 +307,17 @@ DECISION TO ASK THE PLAYER FIRST:
      and Android Keystore stubs that need real bridges. Larger
      scope; needs an Android device or emulator running.
   B. Replay-overlay screen-takeover redesign — multi-session
-     work: move-log scroller, mini-tableau preview, WIN MOVE
+     work. Three sub-pieces shipped post-v0.21.3: WIN MOVE
-     marker on the scrub bar (needs new `Replay::win_move_index`
+     marker (`ab857bb` data field + `52befa6` UI), playback
-     field), playback controls. The smaller floating-MOVE-chip
+     controls (`fbe48ac` pause/resume/step + Space). What
-     piece of B already shipped in v0.21.2 (`2fb2d63`).
+     still needs to land: a move-log scroller and a
+     mini-tableau preview — both layout-heavy pieces that need
+     more vertical real estate than the current banner-only
+     overlay carries, so the natural next finite step is the
+     screen-takeover layout itself (mockup at
+     `docs/ui-mockups/replay-overlay-mobile.html`). The
+     smaller floating-MOVE-chip piece shipped in v0.21.2
+     (`2fb2d63`).
   C. Phase 8 (sync) — local storage scaffolding, self-hosted
      Axum server, `SolitaireServerClient` impl, GPGS stub
      wired into Settings. The biggest open arc by scope; rolls

solitaire_data/src/replay.rs

@@ -147,12 +147,38 @@ pub struct Replay {
     /// [`REPLAY_SCHEMA_VERSION`].
     #[serde(default)]
     pub share_url: Option<String>,
+    /// Index into [`moves`](Self::moves) of the move that triggered
+    /// the win condition (i.e. completed the last foundation pile).
+    ///
+    /// For replays recorded by the live engine this is always
+    /// `Some(moves.len() - 1)` because recording freezes on win — but
+    /// the field is stored explicitly so the playback UI can read it
+    /// directly without re-deriving "the last move was the win" each
+    /// time, and to leave room for future recording semantics that
+    /// might capture post-win state.
+    ///
+    /// `None` for replays loaded from disk that pre-date this field.
+    /// `#[serde(default)]` keeps older `latest_replay.json` /
+    /// `replays.json` files loadable without bumping
+    /// [`REPLAY_SCHEMA_VERSION`] — this is an additive optional
+    /// field, not a schema-breaking change.
+    ///
+    /// Surfaced by the replay-overlay scrub bar's WIN MOVE marker
+    /// (B-2 screen-takeover redesign) when present.
+    #[serde(default)]
+    pub win_move_index: Option<usize>,
 }
 
 impl Replay {
     /// Construct a fresh replay with the current schema version. The
     /// caller fills in the recorded fields; this is the canonical
     /// constructor used by the engine on win.
+    ///
+    /// [`win_move_index`](Self::win_move_index) and
+    /// [`share_url`](Self::share_url) default to `None` — the engine
+    /// uses [`with_win_move_index`](Self::with_win_move_index) at the
+    /// recording site to set the former, and `sync_plugin` writes the
+    /// latter directly when the upload task resolves.
     pub fn new(
         seed: u64,
         draw_mode: DrawMode,
@@ -172,8 +198,24 @@ impl Replay {
             recorded_at,
             moves,
             share_url: None,
+            win_move_index: None,
         }
     }
+
+    /// Builder-style setter for [`win_move_index`](Self::win_move_index).
+    /// Returns `self` so the recording site can chain it onto
+    /// [`Replay::new`]:
+    ///
+    /// ```ignore
+    /// let replay = Replay::new(...).with_win_move_index(Some(recording.moves.len() - 1));
+    /// ```
+    ///
+    /// `None` is a valid input — useful for tests that don't care about
+    /// the WIN MOVE marker's scrub-bar position.
+    pub fn with_win_move_index(mut self, idx: Option<usize>) -> Self {
+        self.win_move_index = idx;
+        self
+    }
 }
 
 /// Rolling history of the player's most recent winning replays.
@@ -737,4 +779,71 @@ mod tests {
 
         let _ = fs::remove_file(&path);
     }
+
+    // -----------------------------------------------------------------------
+    // win_move_index — additive optional field for the WIN MOVE marker
+    // -----------------------------------------------------------------------
+
+    #[test]
+    fn replay_new_defaults_win_move_index_to_none() {
+        let r = sample_replay();
+        assert_eq!(r.win_move_index, None);
+    }
+
+    #[test]
+    fn with_win_move_index_sets_value() {
+        let r = sample_replay().with_win_move_index(Some(3));
+        assert_eq!(r.win_move_index, Some(3));
+    }
+
+    #[test]
+    fn with_win_move_index_accepts_none() {
+        // Passing None through the builder is a valid no-op — useful for
+        // tests / synthetic replays that don't care about the marker.
+        let r = sample_replay().with_win_move_index(None);
+        assert_eq!(r.win_move_index, None);
+    }
+
+    #[test]
+    fn replay_with_win_move_index_round_trips_on_disk() {
+        let path = tmp_path("win_move_index_round_trip");
+        let _ = fs::remove_file(&path);
+
+        let original = sample_replay().with_win_move_index(Some(3));
+        save_latest_replay_to(&path, &original).expect("save");
+        let loaded = load_latest_replay_from(&path).expect("load");
+        assert_eq!(loaded.win_move_index, Some(3));
+        assert_eq!(loaded, original);
+
+        let _ = fs::remove_file(&path);
+    }
+
+    /// Older replay files written before this field was added must still
+    /// load — `#[serde(default)]` keeps `win_move_index` optional and
+    /// defaults missing fields to `None`. This is the contract that lets
+    /// us add the field without bumping `REPLAY_SCHEMA_VERSION`.
+    #[test]
+    fn replay_without_win_move_index_loads_with_none() {
+        let path = tmp_path("legacy_no_win_move_index");
+        let _ = fs::remove_file(&path);
+
+        // Hand-rolled minimal v2 replay JSON with no win_move_index field.
+        let v2_no_field = r#"{
+            "schema_version": 2,
+            "seed": 1,
+            "draw_mode": "DrawOne",
+            "mode": "Classic",
+            "time_seconds": 60,
+            "final_score": 100,
+            "recorded_at": "2026-05-02",
+            "moves": []
+        }"#;
+        fs::write(&path, v2_no_field).expect("write fixture");
+
+        let loaded = load_latest_replay_from(&path).expect("load");
+        assert_eq!(loaded.win_move_index, None);
+        assert_eq!(loaded.schema_version, REPLAY_SCHEMA_VERSION);
+
+        let _ = fs::remove_file(&path);
+    }
 }

solitaire_engine/src/achievement_plugin.rs

@@ -1445,6 +1445,7 @@ mod tests {
                 replay: dummy_replay(),
                 cursor: 0,
                 secs_to_next: 0.0,
+                paused: false,
             };
         app.update();
         assert!(
@@ -1480,6 +1481,7 @@ mod tests {
                 replay: dummy_replay(),
                 cursor: 0,
                 secs_to_next: 0.0,
+                paused: false,
             };
         app.update();
 
@@ -1512,6 +1514,7 @@ mod tests {
                 replay: dummy_replay(),
                 cursor: 0,
                 secs_to_next: 0.0,
+                paused: false,
             };
         app.update();
         *app.world_mut().resource_mut::<ReplayPlaybackState>() =
@@ -1534,6 +1537,7 @@ mod tests {
                 replay: dummy_replay(),
                 cursor: 0,
                 secs_to_next: 0.0,
+                paused: false,
             };
         app.update();
         *app.world_mut().resource_mut::<ReplayPlaybackState>() =
@@ -1559,6 +1563,7 @@ mod tests {
                 replay: dummy_replay(),
                 cursor: 0,
                 secs_to_next: 0.0,
+                paused: false,
             };
         app.update();
         *app.world_mut().resource_mut::<ReplayPlaybackState>() =

solitaire_engine/src/game_plugin.rs

@@ -936,6 +936,11 @@ pub fn record_replay_on_win(
         if recording.moves.is_empty() {
             continue;
         }
+        // Recording freezes on win, so the move that triggered the
+        // win condition is the last one in the list. Storing the
+        // index explicitly lets the playback UI read the WIN MOVE
+        // position directly instead of re-deriving it on every render.
+        let win_move_index = recording.moves.len().checked_sub(1);
         let replay = Replay::new(
             game.0.seed,
             game.0.draw_mode.clone(),
@@ -944,7 +949,8 @@ pub fn record_replay_on_win(
             ev.score,
             Utc::now().date_naive(),
             recording.moves.clone(),
-        );
+        )
+        .with_win_move_index(win_move_index);
         let Some(p) = path.as_ref().and_then(|r| r.0.as_deref()) else {
             // No persistence path configured (e.g. tests / minimal Linux
             // containers without dirs::data_dir). The in-memory replay

solitaire_engine/src/replay_overlay.rs

@@ -28,12 +28,15 @@ use chrono::Datelike;
 
 use crate::font_plugin::FontResource;
 use crate::layout::LayoutResource;
-use crate::replay_playback::{stop_replay_playback, ReplayPlaybackState};
+use crate::events::{DrawRequestEvent, MoveRequestEvent};
+use crate::replay_playback::{
+    step_replay_playback, stop_replay_playback, toggle_pause_replay_playback, ReplayPlaybackState,
+};
 use solitaire_data::ReplayMove;
 use crate::ui_modal::{spawn_modal_button, ButtonVariant};
 use crate::ui_theme::{
-    ACCENT_PRIMARY, BG_ELEVATED_HI, BORDER_SUBTLE, TEXT_PRIMARY, TEXT_SECONDARY, TYPE_BODY,
+    ACCENT_PRIMARY, BG_ELEVATED_HI, BORDER_SUBTLE, STATE_SUCCESS, TEXT_PRIMARY, TEXT_SECONDARY,
-    TYPE_CAPTION, TYPE_HEADLINE, VAL_SPACE_1, VAL_SPACE_2, VAL_SPACE_4, Z_DROP_OVERLAY,
+    TYPE_BODY, TYPE_CAPTION, TYPE_HEADLINE, VAL_SPACE_1, VAL_SPACE_2, VAL_SPACE_4, Z_DROP_OVERLAY,
 };
 
 // ---------------------------------------------------------------------------
@@ -111,6 +114,24 @@ pub struct ReplayFloatingProgressChip;
 #[derive(Component, Debug)]
 pub struct ReplayStopButton;
 
+/// Marker on the Pause / Resume button. Click handler queries for this
+/// and calls [`toggle_pause_replay_playback`] on each press. The
+/// button's label text is repainted in lockstep by
+/// `update_pause_button_label` so it always reflects the action the
+/// next click will perform ("Pause" while running, "Resume" while
+/// paused).
+#[derive(Component, Debug)]
+pub struct ReplayPauseButton;
+
+/// Marker on the Step button. Click handler queries for this and
+/// calls [`step_replay_playback`] — only meaningful when paused
+/// (clicks while running are no-ops because the tick loop would race
+/// the manual advance). The button stays visually present but
+/// unresponsive while the playback is running so the player has a
+/// stable layout to scan.
+#[derive(Component, Debug)]
+pub struct ReplayStepButton;
+
 /// Marker on the small caption sitting below the "▌ replay"
 /// headline. Carries `GAME #YYYY-DDD` (year + chrono ordinal) while a
 /// replay is playing — a compact, monotonically-increasing identifier
@@ -135,6 +156,23 @@ pub struct ReplayOverlayGameCaption;
 #[derive(Component, Debug)]
 pub struct ReplayOverlayScrubFill;
 
+/// Marker for the WIN MOVE tick on the scrub bar — a small absolute-
+/// positioned `Node` anchored at `replay.win_move_index / total` along
+/// the track. Painted in [`STATE_SUCCESS`] so the player can see at a
+/// glance where the winning move sits relative to the playback cursor.
+///
+/// Static — the position is set at spawn time and never changes during
+/// playback (the underlying replay's `win_move_index` is immutable
+/// while `Playing`). Despawned with the rest of the overlay tree when
+/// the replay state transitions back to `Inactive`.
+///
+/// Spawned only when the active replay carries
+/// [`Replay::win_move_index`](solitaire_data::Replay::win_move_index)
+/// `= Some(_)` — older replays loaded from disk pre-date the field
+/// and have no win index to surface.
+#[derive(Component, Debug)]
+pub struct ReplayOverlayWinMoveMarker;
+
 // ---------------------------------------------------------------------------
 // Plugin
 // ---------------------------------------------------------------------------
@@ -160,7 +198,15 @@ impl Plugin for ReplayOverlayPlugin {
         // Putting Stop last means a click in frame N is observed by
         // `react_to_state_change` in frame N+1, which then despawns the
         // overlay in response — a clean state-driven loop.
-        app.add_systems(
+        // Step-button handler dispatches into the same canonical move
+        // / draw events that the tick loop fires. Register them
+        // defensively here so this plugin can run under
+        // `MinimalPlugins` without the playback plugin attached;
+        // `add_message` is idempotent so the duplicate registration
+        // in production (alongside `replay_playback`) is harmless.
+        app.add_message::<MoveRequestEvent>()
+            .add_message::<DrawRequestEvent>()
+            .add_systems(
                 Update,
                 (
                     react_to_state_change,
@@ -168,6 +214,10 @@ impl Plugin for ReplayOverlayPlugin {
                     update_progress_text,
                     update_floating_progress_chip,
                     update_scrub_fill,
+                    update_pause_button_label,
+                    handle_pause_button,
+                    handle_step_button,
+                    handle_pause_keyboard,
                     handle_stop_button,
                 )
                     .chain(),
@@ -357,6 +407,27 @@ fn spawn_overlay(
                         ..default()
                     })
                     .with_children(|wrap| {
+                        // Pause / Resume label is set from the current
+                        // state so a freshly-spawned overlay (which
+                        // currently always starts unpaused) reads
+                        // "Pause". `update_pause_button_label`
+                        // repaints it whenever the state changes.
+                        spawn_modal_button(
+                            wrap,
+                            ReplayPauseButton,
+                            pause_button_label(state),
+                            None,
+                            ButtonVariant::Tertiary,
+                            font_res,
+                        );
+                        spawn_modal_button(
+                            wrap,
+                            ReplayStepButton,
+                            "Step",
+                            None,
+                            ButtonVariant::Tertiary,
+                            font_res,
+                        );
                         spawn_modal_button(
                             wrap,
                             ReplayStopButton,
@@ -375,6 +446,7 @@ fn spawn_overlay(
             // first-frame paint already reflects state instead of
             // popping from 0 → cursor on the first tick.
             let initial_scrub_pct = scrub_pct(state);
+            let win_pct = win_move_marker_pct(state);
             banner
                 .spawn((
                     Node {
@@ -394,6 +466,27 @@ fn spawn_overlay(
                         },
                         BackgroundColor(ACCENT_PRIMARY),
                     ));
+                    // WIN MOVE marker — small green tick anchored at
+                    // `win_move_index / total`. Spawned only when the
+                    // active replay carries the field; older replays
+                    // pre-dating `win_move_index` simply don't get a
+                    // marker. Centered vertically on the 1px track via
+                    // a 3px-tall node offset 1px above the track top so
+                    // 1px sits above and 1px below the track line.
+                    if let Some(pct) = win_pct {
+                        track.spawn((
+                            ReplayOverlayWinMoveMarker,
+                            Node {
+                                position_type: PositionType::Absolute,
+                                left: Val::Percent(pct),
+                                top: Val::Px(-1.0),
+                                width: Val::Px(2.0),
+                                height: Val::Px(3.0),
+                                ..default()
+                            },
+                            BackgroundColor(STATE_SUCCESS),
+                        ));
+                    }
                 });
         });
 
@@ -438,6 +531,33 @@ fn scrub_pct(state: &ReplayPlaybackState) -> f32 {
     }
 }
 
+/// Pure helper — returns the WIN MOVE marker's left-edge position as
+/// a percentage of the scrub track, or `None` when no marker should
+/// be drawn.
+///
+/// `None` is returned in any of these cases:
+/// - The state isn't `Playing` (no replay attached).
+/// - The replay's `win_move_index` is `None` (older replay loaded
+///   from disk pre-dating the field).
+/// - The replay's move list is empty (shouldn't happen for real wins,
+///   but guards the divide-by-zero).
+///
+/// The percentage clamps to `[0, 100]` so a malformed
+/// `win_move_index >= total` (defensive — shouldn't happen) doesn't
+/// position the marker outside the track.
+fn win_move_marker_pct(state: &ReplayPlaybackState) -> Option<f32> {
+    let ReplayPlaybackState::Playing { replay, .. } = state else {
+        return None;
+    };
+    let idx = replay.win_move_index?;
+    let total = replay.moves.len();
+    if total == 0 {
+        return None;
+    }
+    let frac = (idx as f32 / total as f32).clamp(0.0, 1.0);
+    Some(frac * 100.0)
+}
+
 // ---------------------------------------------------------------------------
 // Per-frame text updates
 // ---------------------------------------------------------------------------
@@ -604,9 +724,22 @@ fn format_progress(state: &ReplayPlaybackState) -> String {
 }
 
 // ---------------------------------------------------------------------------
-// Stop button handler
+// Playback-control button handlers
 // ---------------------------------------------------------------------------
 
+/// Pure helper — returns the label the Pause / Resume button should
+/// carry for the given state. "Pause" while running, "Resume" while
+/// paused, empty otherwise (the button is despawned with the rest of
+/// the overlay tree on transitions to `Inactive` / `Completed`, so
+/// the empty branch only fires for one frame around state changes).
+fn pause_button_label(state: &ReplayPlaybackState) -> &'static str {
+    match state {
+        ReplayPlaybackState::Playing { paused: true, .. } => "Resume",
+        ReplayPlaybackState::Playing { paused: false, .. } => "Pause",
+        ReplayPlaybackState::Inactive | ReplayPlaybackState::Completed => "",
+    }
+}
+
 /// Watches the Stop button for `Interaction::Pressed` transitions. On a
 /// click, calls [`stop_replay_playback`] which resets the state to
 /// `Inactive`; the next frame's `react_to_state_change` then despawns
@@ -622,6 +755,82 @@ fn handle_stop_button(
     stop_replay_playback(&mut commands, &mut state);
 }
 
+/// Watches the Pause / Resume button for `Interaction::Pressed`
+/// transitions. On a click, toggles the `paused` flag via
+/// [`toggle_pause_replay_playback`]. The label repaint happens in
+/// [`update_pause_button_label`] on the same frame the state mutation
+/// flushes.
+fn handle_pause_button(
+    mut state: ResMut<ReplayPlaybackState>,
+    buttons: Query<&Interaction, (With<ReplayPauseButton>, Changed<Interaction>)>,
+) {
+    if !buttons.iter().any(|i| *i == Interaction::Pressed) {
+        return;
+    }
+    toggle_pause_replay_playback(&mut state);
+}
+
+/// Watches the Step button for `Interaction::Pressed` transitions. On
+/// a click, advances exactly one move via [`step_replay_playback`].
+/// No-op while playback is unpaused (would race the tick loop) — the
+/// guard lives inside `step_replay_playback`.
+fn handle_step_button(
+    mut state: ResMut<ReplayPlaybackState>,
+    mut moves_writer: MessageWriter<MoveRequestEvent>,
+    mut draws_writer: MessageWriter<DrawRequestEvent>,
+    buttons: Query<&Interaction, (With<ReplayStepButton>, Changed<Interaction>)>,
+) {
+    if !buttons.iter().any(|i| *i == Interaction::Pressed) {
+        return;
+    }
+    step_replay_playback(&mut state, &mut moves_writer, &mut draws_writer);
+}
+
+/// Repaints the Pause / Resume button's label whenever
+/// [`ReplayPlaybackState`] changes. Walks from the marked button
+/// entity to its single child [`Text`] so the spawn path doesn't need
+/// a second marker on the inner node.
+fn update_pause_button_label(
+    state: Res<ReplayPlaybackState>,
+    buttons: Query<&Children, With<ReplayPauseButton>>,
+    mut texts: Query<&mut Text>,
+) {
+    if !state.is_changed() {
+        return;
+    }
+    let label = pause_button_label(&state);
+    if label.is_empty() {
+        // Overlay is mid-teardown; the button entity will despawn
+        // this frame anyway. Skip the repaint to avoid touching a
+        // doomed entity.
+        return;
+    }
+    for children in &buttons {
+        for child in children.iter() {
+            if let Ok(mut text) = texts.get_mut(child) {
+                text.0 = label.to_string();
+                break;
+            }
+        }
+    }
+}
+
+/// Watches `Space` for the keyboard pause / resume accelerator.
+/// UI-first contract from CLAUDE.md §3.3 is satisfied by the on-
+/// screen Pause / Resume button; this is the optional accelerator.
+/// No-op when the playback isn't `Playing` (e.g. while a modal is
+/// open and the player is using `Space` for something else).
+fn handle_pause_keyboard(
+    keys: Option<Res<ButtonInput<KeyCode>>>,
+    mut state: ResMut<ReplayPlaybackState>,
+) {
+    let Some(keys) = keys else { return };
+    if !keys.just_pressed(KeyCode::Space) {
+        return;
+    }
+    toggle_pause_replay_playback(&mut state);
+}
+
 // ---------------------------------------------------------------------------
 // Tests
 // ---------------------------------------------------------------------------
@@ -722,6 +931,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 0,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -745,6 +955,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 5,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -765,6 +976,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 0,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -821,6 +1033,7 @@ mod tests {
                 replay: synthetic_replay(5),
                 cursor: 0,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -857,6 +1070,7 @@ mod tests {
                 replay: synthetic_replay(3),
                 cursor: 1,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -884,6 +1098,7 @@ mod tests {
                 replay: synthetic_replay(7),
                 cursor: 7,
                 secs_to_next: 0.0,
+                paused: false,
             },
         );
         app.update();
@@ -937,6 +1152,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 0,
                 secs_to_next: 0.5,
+                paused: false,
             }),
             0.0,
         );
@@ -945,6 +1161,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 5,
                 secs_to_next: 0.5,
+                paused: false,
             }),
             50.0,
         );
@@ -953,6 +1170,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 10,
                 secs_to_next: 0.5,
+                paused: false,
             }),
             100.0,
         );
@@ -987,6 +1205,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 5,
                 secs_to_next: 0.5,
+                paused: false,
             }),
             Some("GAME #2026-122".to_string()),
         );
@@ -1000,6 +1219,7 @@ mod tests {
                 replay: early_january,
                 cursor: 0,
                 secs_to_next: 0.5,
+                paused: false,
             }),
             Some("GAME #2026-005".to_string()),
         );
@@ -1017,6 +1237,7 @@ mod tests {
                 replay: synthetic_replay(10),
                 cursor: 0,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -1048,6 +1269,7 @@ mod tests {
                 replay: synthetic_replay(8),
                 cursor: 2,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -1063,6 +1285,7 @@ mod tests {
                 replay: synthetic_replay(8),
                 cursor: 6,
                 secs_to_next: 0.5,
+                paused: false,
             },
         );
         app.update();
@@ -1080,4 +1303,295 @@ mod tests {
             "Completed state must read as a fully-filled track",
         );
     }
+
+    // -----------------------------------------------------------------------
+    // win_move_marker_pct + ReplayOverlayWinMoveMarker spawn behaviour
+    // -----------------------------------------------------------------------
+
+    fn win_marker_count(app: &mut App) -> usize {
+        app.world_mut()
+            .query::<&ReplayOverlayWinMoveMarker>()
+            .iter(app.world())
+            .count()
+    }
+
+    #[test]
+    fn win_move_marker_pct_is_none_for_inactive() {
+        assert_eq!(win_move_marker_pct(&ReplayPlaybackState::Inactive), None);
+    }
+
+    #[test]
+    fn win_move_marker_pct_is_none_for_completed() {
+        // `Completed` carries no replay so the marker has no data to
+        // anchor against — the overlay treats this as "no marker".
+        assert_eq!(win_move_marker_pct(&ReplayPlaybackState::Completed), None);
+    }
+
+    #[test]
+    fn win_move_marker_pct_is_none_when_replay_lacks_field() {
+        // Synthetic replay constructor leaves win_move_index as None
+        // (legacy / pre-`ab857bb` path).
+        let state = ReplayPlaybackState::Playing {
+            replay: synthetic_replay(10),
+            cursor: 0,
+            secs_to_next: 0.5,
+            paused: false,
+        };
+        assert_eq!(win_move_marker_pct(&state), None);
+    }
+
+    #[test]
+    fn win_move_marker_pct_is_some_at_correct_position() {
+        // 10 moves, win at index 9 → marker sits at 90 % of the track.
+        // Matches the recording semantic: cursor reaches the marker
+        // exactly when the about-to-apply move IS the win move.
+        let state = ReplayPlaybackState::Playing {
+            replay: synthetic_replay(10).with_win_move_index(Some(9)),
+            cursor: 0,
+            secs_to_next: 0.5,
+            paused: false,
+        };
+        assert_eq!(win_move_marker_pct(&state), Some(90.0));
+    }
+
+    #[test]
+    fn win_move_marker_pct_clamps_to_track_bounds() {
+        // Defensive: if a malformed replay carried `win_move_index >=
+        // total`, the marker must still sit on the track, not past it.
+        let state = ReplayPlaybackState::Playing {
+            replay: synthetic_replay(5).with_win_move_index(Some(99)),
+            cursor: 0,
+            secs_to_next: 0.5,
+            paused: false,
+        };
+        assert_eq!(win_move_marker_pct(&state), Some(100.0));
+    }
+
+    #[test]
+    fn marker_spawned_when_replay_has_win_move_index() {
+        let mut app = headless_app();
+        set_state(
+            &mut app,
+            ReplayPlaybackState::Playing {
+                replay: synthetic_replay(8).with_win_move_index(Some(7)),
+                cursor: 0,
+                secs_to_next: 0.5,
+                paused: false,
+            },
+        );
+        app.update();
+        assert_eq!(
+            win_marker_count(&mut app),
+            1,
+            "marker entity must spawn when replay carries Some(win_move_index)"
+        );
+    }
+
+    #[test]
+    fn marker_not_spawned_when_replay_lacks_win_move_index() {
+        let mut app = headless_app();
+        // Default constructor → win_move_index: None (legacy replay).
+        set_state(
+            &mut app,
+            ReplayPlaybackState::Playing {
+                replay: synthetic_replay(8),
+                cursor: 0,
+                secs_to_next: 0.5,
+                paused: false,
+            },
+        );
+        app.update();
+        assert_eq!(
+            win_marker_count(&mut app),
+            0,
+            "no marker should spawn for a replay pre-dating the field"
+        );
+    }
+
+    #[test]
+    fn marker_despawns_when_replay_state_returns_to_inactive() {
+        let mut app = headless_app();
+        set_state(
+            &mut app,
+            ReplayPlaybackState::Playing {
+                replay: synthetic_replay(8).with_win_move_index(Some(7)),
+                cursor: 0,
+                secs_to_next: 0.5,
+                paused: false,
+            },
+        );
+        app.update();
+        assert_eq!(win_marker_count(&mut app), 1);
+
+        set_state(&mut app, ReplayPlaybackState::Inactive);
+        app.update();
+        assert_eq!(
+            win_marker_count(&mut app),
+            0,
+            "marker must despawn with the rest of the overlay tree"
+        );
+    }
+
+    // -----------------------------------------------------------------------
+    // pause_button_label + pause / step click handlers + keyboard accelerator
+    // -----------------------------------------------------------------------
+
+    /// Read the current text content of the unique pause / resume button.
+    fn pause_button_text(app: &mut App) -> String {
+        let world = app.world_mut();
+        let mut button_q = world.query_filtered::<&Children, With<ReplayPauseButton>>();
+        let children: Vec<Entity> = button_q
+            .iter(world)
+            .next()
+            .map(|c| c.iter().collect())
+            .unwrap_or_default();
+        let mut text_q = world.query::<&Text>();
+        for child in children {
+            if let Ok(text) = text_q.get(world, child) {
+                return text.0.clone();
+            }
+        }
+        String::new()
+    }
+
+    /// Find the unique entity carrying the given button marker.
+    fn unique_button<M: Component>(app: &mut App) -> Entity {
+        let world = app.world_mut();
+        let mut q = world.query_filtered::<Entity, With<M>>();
+        q.iter(world).next().expect("button entity must exist")
+    }
+
+    fn pressed_paused_state(replay_len: usize, cursor: usize) -> ReplayPlaybackState {
+        ReplayPlaybackState::Playing {
+            replay: synthetic_replay(replay_len),
+            cursor,
+            secs_to_next: 0.5,
+            paused: true,
+        }
+    }
+
+    fn running_state(replay_len: usize, cursor: usize) -> ReplayPlaybackState {
+        ReplayPlaybackState::Playing {
+            replay: synthetic_replay(replay_len),
+            cursor,
+            secs_to_next: 0.5,
+            paused: false,
+        }
+    }
+
+    #[test]
+    fn pause_button_label_reads_pause_when_running() {
+        assert_eq!(pause_button_label(&running_state(5, 0)), "Pause");
+    }
+
+    #[test]
+    fn pause_button_label_reads_resume_when_paused() {
+        assert_eq!(pause_button_label(&pressed_paused_state(5, 0)), "Resume");
+    }
+
+    #[test]
+    fn pause_button_label_is_empty_off_state() {
+        assert_eq!(pause_button_label(&ReplayPlaybackState::Inactive), "");
+        assert_eq!(pause_button_label(&ReplayPlaybackState::Completed), "");
+    }
+
+    #[test]
+    fn pause_button_text_swaps_when_state_pauses() {
+        let mut app = headless_app();
+        set_state(&mut app, running_state(5, 0));
+        app.update();
+        assert_eq!(pause_button_text(&mut app), "Pause");
+
+        set_state(&mut app, pressed_paused_state(5, 0));
+        app.update();
+        assert_eq!(
+            pause_button_text(&mut app),
+            "Resume",
+            "label must repaint to Resume on the frame the state pauses"
+        );
+    }
+
+    #[test]
+    fn pause_button_click_toggles_paused_flag() {
+        let mut app = headless_app();
+        set_state(&mut app, running_state(5, 0));
+        app.update();
+
+        let button = unique_button::<ReplayPauseButton>(&mut app);
+        app.world_mut()
+            .entity_mut(button)
+            .insert(Interaction::Pressed);
+        app.update();
+
+        match app.world().resource::<ReplayPlaybackState>() {
+            ReplayPlaybackState::Playing { paused, .. } => {
+                assert!(*paused, "click must flip running → paused");
+            }
+            other => panic!("expected Playing, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn step_button_click_advances_cursor_while_paused() {
+        let mut app = headless_app();
+        set_state(&mut app, pressed_paused_state(5, 0));
+        app.update();
+
+        let button = unique_button::<ReplayStepButton>(&mut app);
+        app.world_mut()
+            .entity_mut(button)
+            .insert(Interaction::Pressed);
+        app.update();
+
+        match app.world().resource::<ReplayPlaybackState>() {
+            ReplayPlaybackState::Playing { cursor, paused, .. } => {
+                assert_eq!(*cursor, 1, "step must advance the cursor by exactly one");
+                assert!(*paused, "step must leave the paused flag untouched");
+            }
+            other => panic!("expected Playing, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn step_button_click_is_noop_while_running() {
+        let mut app = headless_app();
+        set_state(&mut app, running_state(5, 0));
+        app.update();
+
+        let button = unique_button::<ReplayStepButton>(&mut app);
+        app.world_mut()
+            .entity_mut(button)
+            .insert(Interaction::Pressed);
+        app.update();
+
+        match app.world().resource::<ReplayPlaybackState>() {
+            ReplayPlaybackState::Playing { cursor, paused, .. } => {
+                assert_eq!(*cursor, 0, "running-step must not race the tick loop");
+                assert!(!*paused);
+            }
+            other => panic!("expected Playing, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn space_keyboard_toggles_paused_flag() {
+        let mut app = headless_app();
+        // The keyboard handler reads `Option<Res<ButtonInput<KeyCode>>>`
+        // and no-ops when missing — provide it for this test.
+        app.init_resource::<ButtonInput<KeyCode>>();
+        set_state(&mut app, running_state(5, 0));
+        app.update();
+
+        app.world_mut()
+            .resource_mut::<ButtonInput<KeyCode>>()
+            .press(KeyCode::Space);
+        app.update();
+
+        match app.world().resource::<ReplayPlaybackState>() {
+            ReplayPlaybackState::Playing { paused, .. } => {
+                assert!(*paused, "Space must toggle running → paused");
+            }
+            other => panic!("expected Playing, got {other:?}"),
+        }
+    }
 }

solitaire_engine/src/replay_playback.rs

@@ -119,6 +119,15 @@ pub enum ReplayPlaybackState {
         cursor: usize,
         /// Seconds remaining until the next move is dispatched.
         secs_to_next: f32,
+        /// `true` while playback is paused — `tick_replay_playback`
+        /// skips the `secs_to_next` decrement entirely while this is
+        /// set, so the cursor and the timer freeze together. The
+        /// overlay stays mounted (`is_playing()` still returns
+        /// `true`) so the player can see the paused state and the
+        /// Resume / Step controls. Stepping while paused fires the
+        /// next move directly via [`step_replay_playback`] and
+        /// leaves the paused flag untouched.
+        paused: bool,
     },
     /// The replay finished playing back. The overlay swaps the banner
     /// label to "Replay complete" until [`auto_clear_completed_replay`]
@@ -194,6 +203,7 @@ pub fn start_replay_playback(
         replay,
         cursor: 0,
         secs_to_next: REPLAY_MOVE_INTERVAL_SECS,
+        paused: false,
     };
 }
 
@@ -219,6 +229,61 @@ pub fn stop_replay_playback(
     **state = ReplayPlaybackState::Inactive;
 }
 
+/// Toggle the `paused` flag on the active playback. No-op when not
+/// `Playing` (i.e. `Inactive` or `Completed`) — pause has no meaning
+/// in those states. Returns the new paused value, or `None` if the
+/// state wasn't `Playing`.
+pub fn toggle_pause_replay_playback(state: &mut ResMut<ReplayPlaybackState>) -> Option<bool> {
+    if let ReplayPlaybackState::Playing { paused, .. } = state.as_mut() {
+        *paused = !*paused;
+        Some(*paused)
+    } else {
+        None
+    }
+}
+
+/// Advance playback by exactly one move. Only meaningful while paused
+/// — when called on an unpaused playback it would race the
+/// `tick_replay_playback` loop. Returns `true` when a move was fired,
+/// `false` when no-op (state isn't `Playing { paused: true }` or the
+/// cursor is already at the end of the move list).
+///
+/// Stepping the last move transitions the state to `Completed` on
+/// the next `tick_replay_playback` frame — same end-of-list path the
+/// normal advance loop takes.
+pub fn step_replay_playback(
+    state: &mut ResMut<ReplayPlaybackState>,
+    moves_writer: &mut MessageWriter<MoveRequestEvent>,
+    draws_writer: &mut MessageWriter<DrawRequestEvent>,
+) -> bool {
+    let ReplayPlaybackState::Playing {
+        replay,
+        cursor,
+        paused: true,
+        ..
+    } = state.as_mut()
+    else {
+        return false;
+    };
+    if *cursor >= replay.moves.len() {
+        return false;
+    }
+    match &replay.moves[*cursor] {
+        ReplayMove::Move { from, to, count } => {
+            moves_writer.write(MoveRequestEvent {
+                from: from.clone(),
+                to: to.clone(),
+                count: *count,
+            });
+        }
+        ReplayMove::StockClick => {
+            draws_writer.write(DrawRequestEvent);
+        }
+    }
+    *cursor += 1;
+    true
+}
+
 /// Tick system. Runs every frame; only does work when
 /// [`ReplayPlaybackState::is_playing`].
 ///
@@ -249,8 +314,15 @@ fn tick_replay_playback(
         replay,
         cursor,
         secs_to_next,
+        paused,
     } = state.as_mut()
     {
+        // While paused, the cursor and the timer freeze together —
+        // skip the decrement entirely so resuming starts the next
+        // move from a full `secs_to_next` window. Stepping (handled
+        // separately) fires moves directly without touching this
+        // path.
+        if !*paused {
             *secs_to_next -= dt;
             while *secs_to_next <= 0.0 && *cursor < replay.moves.len() {
                 match &replay.moves[*cursor] {
@@ -273,6 +345,7 @@ fn tick_replay_playback(
                 transition_to_completed = true;
             }
         }
+    }
 
     if transition_to_completed {
         *state = ReplayPlaybackState::Completed;